Understanding the Electron-Doping Mechanism in Potassium-Intercalated Single-Walled Carbon Nanotubes

Kröckel C, Preciado-Rivas MR, Torres-Sánchez VA, Mowbray DJ, Reich S, Hauke F, Chacón-Torres JC, Hirsch A (2020)

Publication Type: Journal article

Publication year: 2020

Journal

Journal of the American Chemical Society American Chemical Society

Book Volume: 142

Pages Range: 2327-2337

Journal Issue: 5

DOI: 10.1021/jacs.9b11370

Abstract

Single-walled carbon nanotubes (SWCNTs) can be doped with potassium, similar to graphite, leading to intercalation compounds. These binary systems exhibit a clear metallic character. However, the entire picture of how electron doping (e-doping) modifies the SWCNTs' vibrational spectra as a function of their diameter, chirality, and metallicity is still elusive. Herein, we present a detailed study of the intercalation and solid state reduction of metallic and semiconducting enriched HiPco SWCNTs. We performed a combined experimental and theoretical study of the evolution of their Raman response with potassium exposure, focusing specifically on their radial breathing mode (RBM). We found the charge donated from the potassium atoms occupies antibonding π orbitals of the SWCNTs, weakening their C-C bonds, and reducing the RBM frequency. This RBM downshift with increasing doping level is quasi-linear with a steplike behavior when the Fermi level crosses a van Hove singularity for semiconducting species. Moreover, this weakening of the C-C bonds is greater with decreasing curvature, or increasing diameter. Overall, this suggests the RBM downshift with e-doping is proportional to both the SWCNT's integrated density of states (DOS) ϱ(ε) and diameter d. We have provided a precise and complete description of the complex electron doping mechanism in SWCNTs up to a charge density of -18 me/C, far beyond that achievable by standard gate voltage studies, not being the highest doping possible, but high enough to track the effects of doping in SWCNTs based on their excitation energy, diameter, band gap energy, chiral angle, and metallicity. This work is highly relevant to tuning the electronic properties of SWCNTs for applications in nanoelectronics, plasmonics, and thermoelectricity.

Authors with CRIS profile

Claudia Kröckel Lehrstuhl für Organische Chemie II Frank Hauke Lehrstuhl für Organische Chemie II Andreas Hirsch Lehrstuhl für Organische Chemie II

Involved external institutions

Universidad de Investigación de Tecnología Experimental (Yachay Tech) EC Ecuador (EC) Freie Universität Berlin DE Germany (DE)

How to cite

APA:

Kröckel, C., Preciado-Rivas, M.R., Torres-Sánchez, V.A., Mowbray, D.J., Reich, S., Hauke, F.,... Hirsch, A. (2020). Understanding the Electron-Doping Mechanism in Potassium-Intercalated Single-Walled Carbon Nanotubes. Journal of the American Chemical Society, 142(5), 2327-2337. https://dx.doi.org/10.1021/jacs.9b11370

MLA:

Kröckel, Claudia, et al. "Understanding the Electron-Doping Mechanism in Potassium-Intercalated Single-Walled Carbon Nanotubes." Journal of the American Chemical Society 142.5 (2020): 2327-2337.

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